1. Field of the Invention
The present invention relates to an engine having an oil pump. More particularly, the present invention relates to a coupling structure, or a driving transmission structure, between a crankshaft of the engine and a pump shaft of the oil pump.
2. Description of the Background Art
A conventional engine having an oil pump is shown in FIGS. 9 and 10, which are from the official gazette of Japanese Patent Laid-Open No. Hei. 9 301286. The engine 1 shown in FIGS. 9 and 10 is carried on a small-sized boat. The engine 1 includes a supply pump 2 (see FIG. 10) for supplying oil from an oil tank 4 into the engine 1, and a recovery pump 3 for recovering oil, which has lubricated the inside of the engine 1, into the oil tank 4. The pumps 2 and 3 are disposed on shafts 2a and 3a which extend in parallel to a crankshaft 5 of the engine, and are driven to rotate by the crankshaft 5 through a transmission gear (not shown). Since the pumps 2 and 3 of the engine 1 described above are each respectively disposed on the shafts 2a, 3a parallel to the crankshaft 5, and are driven to rotate by the crankshaft 5 through the transmission gear (not shown), there is a disadvantage that the driving structure therefor is complicated, and also an increased number of parts are required.
It is therefore an object of the present invention to provide an engine with an oil pump wherein the oil pump can be driven with a simple structure and also the number of parts is decreased. To attain the object described above, an oil pump is disposed on an extension line of a crankshaft of the engine, and a coupler interconnects the crankshaft to a shaft of the oil pump. The coupler includes a first joint member provided at an end portion of the crankshaft, and a second joint member provided at an end portion of the shaft of the oil pump. The two joint members are coupled to each other on the same axial line within a cover of the engine.
The joining portions of both joint members are formed with concave and convex portions. Faces of the convex portions which oppose driving transmission faces of the convex portions are formed as inclined faces for guiding the convex portions of the opposing joint member. The joint member on the crankshaft is secured by being fastened together with an ACG rotor provided at an end portion of the crankshaft.
Because the oil pump is disposed on an extension line of the crankshaft, and the joint member provided at an end portion of the crankshaft and the joint member provided at an end portion of the pump shaft are coupled to each other on the same axial line, the requirement for a conventionally required transmission gear is eliminated. In the present invention, the oil pump can be driven with a simple structure, and the number of parts can be reduced. Further, since the two joint members are coupled to each other within the cover of the engine, the space for coupling the crankshaft and the pump shaft to each other may be small. However, because the coupler is located within the cover and cannot be visually observed, there is the possibility that the coupling operation may be difficult.
In the present invention, even if the coupling portions of the two joint members are within the cover and cannot be visually observed, the coupling operation can be readily performed since the joining portions of the two joint members are formed with the concave and convex portions, wherein faces of the convex portions which oppose driving transmission faces of the convex portions are formed as inclined faces for guiding the convex portions of the opposing joint member.
As described above, with the present invention, the oil pump can be driven with a simple structure, and the number of parts can be reduced. In addition, while the space for coupling the crankshaft and the pump shaft may be small, the coupling operation of the two joint members can be performed readily. Also, since the joint member of the crankshaft side is secured by being fastened together with the ACG rotor which is provided at an end portion of the crankshaft, the ACG rotor and the joint member can be provided efficiently in a small space with a small number of parts.
An oil tank is connected to the oil pump, and is disposed above and very close to the oil pump. The oil pump includes an oil supply pump and an oil recovery pump which are driven to rotate by a common shaft. Since the oil tank is disposed above and very close to the oil pump, the space above the oil pump can be utilized efficiently, and members around the engine can be compactly configured. In addition, since pipes for connecting the oil pump and the oil tank to each other can be made short, oil can be circulated efficiently.
Since the oil supply pump and the oil recovery pump are rotated by a common shaft, the engine can be compactly formed when compared with an engine of the configuration wherein the oil supply and oil recovery pumps are disposed on individual shafts, and driven to rotate by transmissions as in the conventional engine with an oil pump shown in FIG. 10.
Where the oil supply pump and the oil recovery pump are driven to rotate by the common shaft, although the length of the pump in its axial line direction becomes comparatively large, the space above the oil pump can be utilized effectively by disposing the oil tank above and very close to the oil pump, and members around the engine can be compactly configured. In addition, not only it is possible to make the pipes for connecting the oil pump and the oil tank to each other short to augment the circulation efficiency of oil, but it is also possible to concentrate the pipes for the oil supply pump and the pipe for the oil recovery pump.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.